<p>Currently, two main approaches are used in Life Cycle Sustainability Assessment (LCSA), the comparative and the integrated approaches. Comparative approaches employ multiple indicators and visualizations to assess LCSA, whereas integrated approaches aggregate the impacts across the three pillars of LCSA into a single sustainability index. However, both methods tend to be either complex for decision-making or involve subjectivity. This paper addresses these limitations by proposing a statistics-based aggregation method that reduces complexity and subjectivity in LCSA. The theory behind the proposed method is the conceptual equation of LCSA, where LCSA = Life Cycle Assessment (LCA) + Life Cycle Costing (LCC) + Social Life Cycle Assessment (S-LCA). Since the method aggregates impacts, its logic can be represented using a Venn diagram, and probability rules are applied for the aggregation. Impact categories in LCA, LCC, and S-LCA are quantified following standardized LCA steps. The method constructs cumulative distribution functions (CDFs) for each impact category, with scores computed from their respective CDFs. Probability rules are applied to aggregate the impact categories. A case study on crumb rubber production demonstrates the method’s applicability, showing that the resulting LCSA impact score reflects the geographical location of the process and is sensitive to the selected impact categories. A step-by-step procedure is also provided to guide implementation.</p>